Motorcycle suspension apparatus

ABSTRACT

Each wheel suspension member includes a pair of telescoping tubes, one connected to the cycle frame and the other connected to the wheel axle. As the wheel receives a perturbation, the tubes are telescoped further within one another which forces an enclosed hydraulic fluid through restricting orifice means to damp the effect received at the upper cycle frame. Simultaneously, an enclosed coil spring is compressed by the same action, which also serves to dampen shock and vibration effect. Conduiting for the hydraulic fluid isolates the fluid from a substantial length of the coil spring, thereby obviating fluid entrapment by the spring. On resuming rest condition the coil spring returns the telescoped tubes to their original relationship, at which time the hydraulic fluid returns through the orifice means, again without contacting the major spring length.

United States Patent 1 51 Aug. 29, 1972 -Rickard [54] MOTORCYCLESUSPENSION APPARATUS [72] Inventor: Donn J. Rickard, 1726 Bender Ave.,.Glendora, Calif. 91740 [22] Filed: Sept. 11, 1970 [21-] Appl. No.:71,301

521' US. Cl ..267/64, 267/34 [51] Int. Cl. ..Fl6f 5/00 [58]FieldolSeareh ..267/64, 34, 8

p [56] References Cited UNITED STATES PATENTS 3,447,797 6/1969 Roberts..267/64 2,259,589 -l0/l94,l Ehleicher ..267/34 1571 ABSTRACT Each wheelsuspension member includes a pair of telescoping tubes, one connected tothe cycle frame and the other connected to the wheel axle. As the wheelreceives a perturbation, the tubes are telescoped further within oneanother which forces an enclosed hydraulic fluid through restrictingorifice means to damp the effect received at the upper cycle frame.Simultaneously, an enclosed coil spring is compressed by the sarneaction, which also serves to dampen shock and vibration eflect.Conduiting for the hydraulic fluid isolates the fluid from a substantiallength of the coil spring, thereby obviating fluid entrapment by thespring. On resuming rest condition the coil spring returns thetelescoped tubes to their original relationship, at which time thehydraulic fluid returns through the orifice means, again withoutcontacting the major spring length.

MOTORCYCLE SUSPENSION APPARATUS The present invention relates generallyto motorcycles, and, more particularly, to wheel suspension apparatusfor a motorcycle providing improved shock and vibration absorptioncharacteristics.

BACKGROUND OF THE INVENTION It has been conventional in the past toprovide the front wheel of a two-wheeled motorcycle with a suspensionsystem for absorbing or damping shocks and vibrations to provide therider with a more comfortable and safer ride. The need for such shockand vibration absorption has been considerably increased in recentyears, particularly with the advent of off-theroad or dirt bike ridingfor general recreation and racing, in which the vehicle traversesterrain that is highly uneven and bumpy as compared to a typical roadsurface. It is apparent that in driving a motorcycle under off-roadconditions, unless efficient and continuously operating shock andabsorption means are provided, not only will the riding qualities beless than desirable, but such riding can be dangerous to the driver inthat a sudden shock may throw the motorcycle out of control.

One conventional approach in the past has been to mount the front wheelto the cycle frame by coil springs, which, through their inherentresiliency, absorb a certain amount of the vibrations and shocksproduced during riding. Such springs are useful for this purpose,however, they are only effective for a limited range of shock andvibration dependent upon the physical parameters of any given spring.For example, if a set of springs are made sufficiently resistive inorder to be able to accommodate relatively high shock loads, they willpresent little resiliency to lower level shocks and vibrations.

Another approach has been to utilize a hydraulic device operatingsomewhat similarly to a conventional dashpot, in which the front wheelof the cycle is interrelated to the cycle frame through the intermediaryof a hydraulic fluid for damping. Again, this approach alone is notcompletely satisfactory in that the resistance to shock of such a deviceis proportional to the speed with which it is applied, such that veryhard and quick shocks are resisted with a high amount of force, i.e., donot provide resilient damping.

Accordingly, to obtain a broader range of accommodation of shocks andvibrations, the more recent approach has been to combine the action of ahydraulic device and a coil spring in the same suspension apparatus. Themost widely accepted version of such combination apparatus encloses thecoil spring and the hydraulic device within the same housing, so thatall that is seen from the exterior is two sets of telescoping tubesinterconnecting the bike frame and front wheel, one at each side of thewheel. A consistent problem encountered in the use of known combinationspringhydraulic systems is that on initiating operation of a cycle overrough or uneven terrain, a relatively high performance level isattained, after which performance rapidly degrades. More particularly,it has been found that in this kind of suspension means, the hydraulicdevice, upon applying continuing series of shocks to the cycle frontwheel suffers a loss in damping efficiency. Although other factors mayinfluence operational efficiency, it is believed that the hydraulic'fluid used, shortly after initiation of operation, becomes entrappedwithin the coil spring loops and therefore is not available for use inthe hydraulic device. Of course, if the cycle is allowed to rest, thehydraulic fluid will drain off the spring and again be available for useby the hydraulic device, which accounts for the cyclic high-efficiency,low efficiency operation experienced with such systems.

OBJECTS AND SUMMARY OF THE INVENTION It is, therefore, a primary aim andobject of this invention to provide motorcycle shock absorptionapparatus of improved continuous performance operation.

Another object of the invention is the provision of motorcycle wheelsuspension apparatus including spring and hydraulic shock absorptionmeans of sub-' stantially constant efficiency during extended use.

Yet another object of the invention is the provision of a combinationspring-hydraulic suspension apparatus as in the above objects in whichthe hydraulic fluid is maintained isolated from the spring duringoperation.

In accordance with the practice of the present invention, a motorcyclefork for interrelating the front wheel of the cycle and the frameincludes a pair of suspension members, one at each side of the wheel,and each one of which includes a pair of telescoping tubes, oneconnected to the frame and the other connected to the front wheel axle.As the wheel receives a shock or vibration, the tubes are caused to betelescoped further within one another which forces an enclosed hydraulicfluid through a restricting orifice means to dampen the effect on theupper frame of the cycle. Simultaneously, an enclosed coil spring iscompressed by the same action, which also serves to dampen shock andvibration effect. Conduiting for the hydraulic fluid isolates the fluidfrom a substantial length of the coil spring, thereby obviating fluidentrapment by the spring. On the cycle resuming rest condition, the coilspring returns the telescoped tubes to their original relationship, atwhich time the hydraulic fluid returns through the orifice means, againwithout contacting the major length of the spring.

DESCRIPTION OF THE DRAWINGS FIG. I is a front elevation view of amotorcycle, showing the shock absorption suspension of the presentinvention.

FIG. 2 is a sectional, elevational view of the wheel suspension of thepresent invention.

FIG. 3 is an enlarged sectional partially fragmentary view of thesuspension of FIG. 2.

FIG. 4 is a transverse sectional view taken along line 4-4 of FIG. 3.

DESCRIPTION OF A PREFERRED EMBODIMENT FIG. 1 depicts a generally frontalview of a motorcycle it) having a body frame 11, handlebars 12, frontwheel 13 and a fork 14 interrelating the wheel, frame and handlebars.More specifically, the fork 14 includes a pair of suspension members 15and 16 which are rotatably journaled at their lower ends with the frontwheel axis 17 providing a resilient suspension for the front wheel in away that will be described.

Turning now to FIG. 2, each suspension member 15, 16 is seen to includean open-ended, hollow cylinder or tube 18, frequently referred to as astanchion, which has its lower end telescopingly received within theopen end of a second hollow tube or cylinder 19, sometimes referred toas a slider. The relative dimensions of the tubes 18 and 19 are such asto provide a close, sliding fit when they are telescoped together, thatis, sufficiently loose to prevent binding or galling, and yet not spacedenough to permit cooking.

The lower closed end of the slider tube 19 includes a flange 20extending outwardly in the long direction of the tube and via whichinterconnection is made to the front wheel axis in a conventionalmanner.

Affixed to the inner end wall 21 of the slider 19 for extending upwardlycoincident with the tube axis is a damper tube means 22 comprisinghollow tube member 23 terminating at its lower end in a mounting boss24, and a collar 25 with a pair of circular flanges 26 and 27 thereonspaced from the other end of the member 23. Several openings 28 areprovided in the tube adjacent the boss 24. The damper tube means 22 isintegrally secured to the end wall 21 by a threaded means 29.

An extension cylinder 30 of outer diameter permitting free slidingreceipt within the stanchion 18 has an axially located longitudinal bore31 extending throughout its complete length. The bore lower end isreceived onto the upper terminus 32 of the tube member 23 with the lowerend wall of the extension cylinder contactingly engaging flange 27.

The upper end opening of the extension cylinder bore 31 is of reduceddiameter as at 33 and into which is fitted one end of an elongatedcylindrical conduit 34. A circular flange 35 is secured to the conduitat a point spaced slightly from its lower end and rests on the uppersurface of the extension cylinder 30 when the conduit end is receivedwithin 33. A plurality of openings 36 are formed in the conduit sidewall in the region immediately adjacent flange 35.

An elongated compression coil spring 37 is received within the stanchion18 with its lower end bearing against flange 35. An open-ended isolationtube 38 of outer diameter slightly less than the inner diameter ofspring 37 is received within the spring from its upper end and issupported therein by end flange 39. The lower end of isolation tube 38extends substantially below and in space surrounding relationship to theupper end of conduit 34 throughout operation for a purpose that will beclarified below. The upper end of stanchion 18 is closed by a threadedplug 40, while its lower open end includes wall portions 41 for engagingflange 26 of collar 25 to limit stanchion upward movement.

Initially, with the motorcycle at rest, hydraulic fluid (oil) is at theapproximate level shown in FIG. 2, i.e., below the upper end of slider19, but above the openings 36. Accordingly, the entire lower reaches ofthe slider tube 19, the bore 31 of the extension cylinder and theinterior of tube member 23 are filled with the hydraulic fluid. Asshocks and vibrations are applied to the front wheel, the slider movesupwardly on the stanchion compressing the hydraulic fluid in the lowerreaches of the slider, causing it to move through openings 28, upwardlythrough tube member 23, the core 31, conduit 34, and, if the shock orvibration is of sufficient strength, the fluid will spill out the end of34 to drain downwardly along the conduit 34 or along the inner wall ofthe isolation tube 38. Also, at this same time the upward movement ofthe slider relative to the stanchion compresses the spring 37. Onreassumption of the rest condition, the spring distends and thehydraulic fluid moves downwardly through 34, either directly along itsmain bore or via openings 36, to exit at openings 28 filling the lowerreaches of 19. in any event, the hydraulic fluid which is emitted from34 during the pressure stroke of the suspension member does not becomeentrapped by the spring loops, but moves along an isolated path forreentry into the lower end of the chamber of the slider 19.

There is provided in accordance with the practice of this invention animproved suspension apparatus which efiects damping of shocks andvibrations at a substantially continuous high level of efficiency.Moreover, the described suspension obtains the combined benefit ofhydraulic damping and coil spring damping without the lowered efficiencyin hydraulic action experienced in known prior apparatus of the samegeneral kind.

What is claimed is:

1. Suspension apparatus, in combination, comprising:

first hollow tube means having a closed end and an open end;

second hollow tube means having a closed end and an open end, with itsopen end telescopingly related to the open end of the first tube means,said tubes being generally vertically arranged with the closed end ofthe second tube means disposed at the lower end;

hydraulic damper means having upper and lower ends secured to the innerclosed end of said second hollow tube means and extending upwardlywithin both said first and second hollow tube means, said damper meansincluding, means unitary therewith and spaced from the damper meansupper and lower ends for sliding contact with the internal wall surfaceof said first tube means, and wall means defining a continuous bore witha first outer opening adjacent the upper end, a second i and extendingfrom its upper end for an extent sufa ficient to enclose a major portionof the upper end of the damper means including the first opening; and

a supply of hydraulic fluid received within the second tube means suchthat applied perturbations to said tube means are clamped by thecombined action of the spring and hydraulic fluid and on cessation ofthe perturbations the hydraulic fluid enters the about the upper endportions of the hollow tubular member.

3. Suspension apparatus as in claim 2, in which the means unitary withthe damper means includes an extension cylinder of outer diameterproviding a close fit within the first tube means; the hollow tubularmember having its lower end mounted to the extension cylinder.

1. Suspension apparatus, in combination, comprising: first hollow tubemeans having a closed end and an open end; second hollow tube meanshaving a closed end and an open end, with its open end telescopinglyrelated to the open end of the first tube means, said tubes beinggenerally vertically arranged with the closed end of the second tubemeans disposed at the lower end; hydraulic damper means having upper andlower ends secured to the inner closed end of said second hollow tubemeans and extending upwardly within both said first and second hollowtube means, said damper means including, means unitary therewith andspaced from the damper means upper and lower ends for sliding contactwith the internal wall surface of said first tube means, and wall meansdefining a continuous bore with a first outer opening adjacent the upperend, a second outer opening adjacent the lower end, and a third outeropening above the unitary means spaced downwardly from said firstopening; a compression coil spring received within said first tube meanshaving one end secured against movement within said first tube means andits other end engaging the means unitary with the damper means; thirdhollow tube means received within the spring and extending from itsupper end for an extent sufficient to enclose a major portion of theupper end of the damper means including the first opening; and a supplyof hydraulic fluid received within the second tube means such thatapplied perturbations to said tube means are damped by the combinedaction of the spring and hydraulic fluid and on cessation of theperturbations the hydraulic fluid enters the second and third openings,moves along the damper means bore and exits through the first openinginto the lower end of the second tube means.
 2. Suspension apparatus asin claim 1, in which the damper means includes a hollow tubular memberthat extends upwardly within the first tube means and spring, the upperopen end of which comprises said first bore opening; and said third tubemeans being received about the upper end portions of the hollow tubularmember.
 3. Suspension apparatus as in claim 2, in which the meansunitary with the damper means includes an extension cylinder of outerdiameter providing a close fit within the first tube means; the hollowtubular member having its lower end mounted to the extension cylinder.